Many audio devices become subject to audible noise after certain test patterns. For instance, sometimes a high level signal followed by a mute or low level signal can produce a phenomenon called idle noise or idle tones. Idle tones are the unwanted appearance of partial artifacts in an output signal that were not present in the original input signal. There are a number of techniques for mitigating idle noise in circuits. Most of the techniques for mitigating the idle noise or tones involve the use of additional filtering components.
Adding additional filtering components to an audio system can, however, be undesirable. For instance, adding a filtering component to an audio baseband chip consumes valuable chip real estate and can increase the cost of the baseband chip. Similarly, external filtering components increase the cost of an audio system because they require relatively expensive components (e.g., inductors, resistors and capacitors) to implement. Accordingly, there is a need for systems and methods that eliminate unwanted noise or idle tones from an audio signal without relying on internal or external filtering components.